connectd tells master about every disconnection, and master knows
whether it's important to reconnect. Just get the master to invoke a new
connect command if it considers the peer important!
The only twist is timeouts: we don't want to immediately reconnect if
we've failed to connect. To solve this, connectd passes a 'delaytime'
to the master when a connection fails, and the master passes it back
when it asks for a connection.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>